Spirit in the Sky Fuzz
This project started as a request to recreate the fuzz sound in the song Spirit in the Sky by Norman Greenbaum. If you are familiar with the gear talk that has been going on about this song, no one really knows what kind of fuzz circuit was used to create that signature sound. IIRC, the fuzz was actually an unidentified homemade circuit built into the guitar.
Although there are plenty of good recommendations for recreating Spirit in the Sky sound, I decided go with my own instinct on sound and my experience building many different fuzz circuits. Since I could essentially "tune" any fuzz circuit to achieve what I want it to sound like, I decided to go with the Fuzz Face circuit because of its tweakability and simplicity. The Fuzz Face needs no introduction and certainly when the vintage originals are costing $1000+ these days. Love it or hate it, this widely known fuzz is so simple that it's highly recommended as a must-build circuit. This must have been my 1XXth time that I've built a Fuzz Face.
The requester did not have a good experience with Fuzz Faces in the past. So I wanted to not only capture the Spirit in the Sky sound, but also the best Fuzz Face sound in its stock form! The request was to use the best parts possible. So I got some vintage NOS components and personally hand picked germanium transistors with lowest noise while providing good fuzz sound. You won't see any trim pots in here because I've done the math and bread boarding to get the exact resistor values needed to set the optimal biasing points for both transistors. One thing about Fuzz Face circuit is that both transistors need to be biased to make it perform at its best. This is due to the inconsistency in the germanium transistors. You could potentially get away with biasing only the second transistor (or none at all), but in my experience, that would only get you so far from being the best sounding fuzz.
Below is the finished pedal. Notice the 4 knobs compared to 2 knobs on original Fuzz Face. The extra 2 knobs are for BIAS and BASS control. BIAS sets the second transistor from hot to cold biasing. This gives different shades of fuzz sound from over-saturated to spluttery-dying-battery sound. BASS sets the amount of "thickness" of fuzz. With these two controls added, dialing the Spirit in the Sky sound, stock Fuzz Face sound, and other fuzz sound is matter of few knob twists.
It's important to note that knowing how to use a fuzz pedal matters. Just like many amps, fuzz pedals are instruments and need to be used with interaction in mind. From pickup controls on the guitar to amp settings, all of that matters when dialing a fuzz sound. Understanding this interacting relationship between instruments should reward you with plethora of fuzzy goodness!
